CurtPalme.com Home Theater Forum

[lyd]

I thought I had read somewhere that it was bad to leave the projector in standby on a regular basis, so I have never hit the standby button and always turn it off with the power button on the remote.

But yesterday I noticed that when I do that the "standby" indicator light is lit. Should I be unplugging it completely between uses instead?

lyd

[Joust]

IIRC, Standby leaves some voltage on the tubes.

[Zebu Fellenz]

My understanding is that standby on a marquee is a picture mute that leaves the projector fully powered up. Hitting the power button turns almost everything off but the LVPS fans.

I'm not sure if voltage is still going to the tubes in POWER OFF

[kschmit2]

It depends on the PJ.
NECs pretty much cut all power when in standby (tubes get no power at all). Basically the set is off, and will simply accept remote commands to power on again. Power Consumption will be close to 0.
Much like an old CRT TV in standby.

On other brands (Marquee e.g.) standby is a condition where the PJ is fully powered up, with the exception that the picture is muted. Tubes are heated, ready to fire at the press of a button. Tubes age with every minute of standby (just not as much as if they were really projecting an image). Electronics are affected the same way.

[lyd]

I appreciate the responses, but I'm not quite clear on this yet. Is turing the power off on the remote and leaving the thing plugged in fine, then?

Like I said, I thought it was 'till now, but noticing that the light labeled "standby" is lit when in this state has me wondering.

lyd

[Joust]

You can leave it plugged in. thats teh way it was designed.
If it goes for long periods not being used, then, I would unplug it.

[lyd]

'Kay, thanks.

I've been using it pretty much every day since I got it, so it sounds like what I've been doing should be fine. (Those "the tubes will last me 15 years!" calculations went right out the window. I am having so much fun with this thing I have been watching at least one movie a day, not to mention all the futzing around time. )

lyd

[Curt Palme]

To answer the post... hang on, I'll tell you.

[Curt Palme]

To answer the post... hang on, I'll tell you.

[lyd]

[garyfritz]

With a Marquee:

* If it's unplugged, no current goes to the tubes. (Obviously!)

* If it's plugged in but not turned on, the LVPS fans spin slowly and a low current goes to the tube cathodes ("heaters"). Don't ask me why, since it doesn't seem to help them fire up any faster. This is the "OFF" state.

* If it's turned on, the fans are at full speed, the tubes are lit. This is the normal "ON" state.

* When it's "ON," if you hit the STANDBY button, the tubes go black but other than that it is fully on. This is "STANDBY."

Supposedly the partly-powered "OFF" state causes no wear.
The "ON" state causes normal wear: it burns electrons off the cathodes and also produces normal phosphor wear.
The "STANDBY" state causes no phosphor wear, but it DOES heat the cathodes just as if the projector was on.

The problem you often see with Marquees is when someone ran them 24/7 in "STANDBY" mode, only turning them "ON" when needed. You might see 2000 hrs of "run" time and 50,000 hrs of "standby" time. Because the tubes have few hours of phosphor-wearing "on" time, the phosphor might be minty white. But because the cathodes were heated for 52,000 hours, their electron emission drops way down. You have to run the G2s way too high, or you might not get any picture out of them at all.

"STANDBY" is fine if you just want a "video mute" -- blank the screen for a while. Maybe you're testing something and want the projector to warm up but you don't want to burn any patterns into the tubes, or something like that. If you're not going to use the projector for an hour or two, STANDBY just wastes power -- turn it off. If you're not going to use it for a week or two, I'd unplug it.

[Curt Palme]

[Curt Palme]

[lyd]

[DEADCRT]

Leaving small current on "heaters" ( filament ) on "stand" by is very old idea. According to long experience with "normal" picture tubes( also and b&w tubes ), cathode ( not "heater" ) has very bad operating mode when it's not fully "heated", but high voltage is already applied to anode ( and all grids ). It reduces lifetime ( emission ) of the cathode. It happens on all semiconductor based TV sets ( CRT's are the only tubes in PJ
This is one of the reasons why picture tubes lasted much longer on tubes based tv sets . Simply horizontal deflection tube goes in to operating mode almost at the same time as picture tube is fully heated . Horizontal deflection circuit was also source of high voltage.
So leaving "warm" cathode is very good way to make tube work longer. The main art here is what current must be left during standby. If it's too low - there is no sense to do that ; if it's to high - cathode life time is reduced . There were statistics for some TV tubes - what filament voltage must be applied during stand by.
Another good way to avoid this is to delay high voltage until tube is heated normally. There is no need for stand by filament in this case .
There were some DIY kits and schematics for both methods. Personally I used first with great success. Bay the way, this method gives almost instant normal image after going from stand by to normal operation. This not means that video is muted or something similar.
I also saw very old semiconductor German TV set with stand by filament. It had many many years and picture was very nice.
Darius

[Tim in Phoenix]

[garyfritz]

Thanks for the background, Darius. One quibble: on my 8500 at least, the "warm" filaments don't seem to speed up the start-up time very much. They still take a while to wake up, roughly as long as other projectors I've used. Not sure if that's typical, but that's what mine does.

[DEADCRT]

If in stand by mode deflections circuits were operating, power consumption in this mode must be almost the same as in operation mode with blanked picture. Most power goes to deflection, not for electron beam. In CRT projector case another power circuit with high power requirement is convergence .
Typical ,about 26" colour picture tube, has max beam current 0.8-1.1 mA ( this is margin where current limitation circuit begins limit beam current). Anode voltage here is about 25kV so you have about 25W power to beam when tube works at maximum.
All these "calculations" is for tv set, but in projector case it's almost the same.
I have Barco701s with run time about 18 000 h. with original tubes. Phosphor looks like a completely new, focus is also good.
So most of it's run time was spend in stand by. I hope that Barco found right standby filament voltage
In my experience, if projector is switched on frequently , it's better to leave it in stand by mode if lower filament is used in this mode.
Another plus of "warm" tube during stand by is that cold "heater" has few times lower resistance than "hot". This means filament current at start from "cold" condition is higher too. If tube has bad connection of the "heater" inside , it can be disconnected form pins. I have only few such cases. It's more theoretical than common case. Any way, if you see bright wire
inside the tube somewhere between pin and "heater" for "heating up" time ( it's about 0.3-0.5 sec ), this tube can fail during one of the powering up.

Another interesting very old idea. It's out of topic, but ...
It was possible to see projected cathode image on screen surface in old b&w ( keep in mind that they are ES ) tubes.
Image is not very brigth , but you can clearly see dead cathode zones ( they are dark due bad emission ). You can also estimate left operating time of the cathode.
Whole idea relays on applying different from normal grids voltages . Electro-optical system ( all grids inside the tube ) focuses beam on the screen not as point ( as is in normal operation ). In this case any beam deflection is not used at all.
So I think it's possible to see image of the cathode on ES projection tube too.
In EM case , I think, it's possible too. Here we have different focusing method, so grid voltages and focusing current will be different.